Search

Three‐lobe morning glory (Ipomoea triloba L.) is an annual weed, which presents vigorous growth, long cycle, and tolerance to glyphosate. Thus, knowledge of aspects related to germination and behavior in the seed bank of this species are essential for the adoption of appropriate management practices to reduce the population in agricultural fields. Therefore, the objective of this work was to characterize the requirements for three‐lobe morning glory germination, perform field emergence modeling using thermal and hydrothermal time models, and determine the longevity of the seed bank. Eight temperatures and 10 water potentials were tested in the laboratory to determine the base temperature and water potential for seed germination. For the modeling of the emergence, field experiments were conducted between the years 2014 and 2018 considering three sampling times (10/20, 11/10, and 12/01), which coincide with the sowing times of summer annual crops. To evaluate the longevity and persistence of the seed bank, a factorial experiment was conducted in which factor A consisted of three burial depths and factor B consisted of five harvesting times. Base values for three‐lobe morning glory emergence are base, optimum, and maximum temperatures of 12.32, 29.82, and 43.31°C, respectively, and base water potential of −0.80 MPa. Both models are adequate to predict the emergence of three‐lobe morning glory in the three sampling times. The species has a persistent seed bank, in which the greater the depth of seed burial, the greater the longevity of the seed bank, and can remain viable for up to 16 months. [ABSTRACT FROM AUTHOR]

Herbicide promotes physiological and biochemical changes even in tolerant species. The objective of this study was to evaluate the interference of the herbicides clodinafop-propargyl and 2,4-D in the antioxidant system of wheat, and iodosulfuron-methyl in wheat and ryegrass. Two studies, divided into three experiments, were conducted in an entirely randomized design in a greenhouse and phytotron. The first study tested herbicides iodosulfuron-methyl, clodinafop-propargyl, 2,4-D, and a control without application in wheat. The second, divided into two experiments with wheat and ryegrass, tested iodosulfuron-methyl doses (0, 1.75, 3.5, and 7.0 g a.i. ha-1). The variables analyzed were the concentrations of chlorophylls a, b, carotenoids, hydrogen peroxide (H2O2), lipid peroxidation (TBARS), electrolyte leakage, and antioxidant system activity. The herbicide treatments iodosulfuron-methyl, clodinafop-propargyl, and 2,4-D decreased the concentrations of chlorophylls and carotenoids in wheat plants. The herbicides promoted oxidative stress with increased H2O2 and TBARS concentrations. Increasing the dose of iodosulfuron-methyl provided a reduction in the activity of the enzymatic antioxidant system in wheat and ryegrass. [ABSTRACT FROM AUTHOR]